1. Field of the Invention
The invention relates to an oscillation decoupling device with a load-receiving element which is mounted in an oscillating manner relative to a support unit at least along an active direction along which the at least one part of the load is applied, and with at least one sensor-actuator unit which detects an oscillation of the element due to the load and acts against the oscillation of the element by means of actuators.
2. Description of the Prior Art
In almost all fields of the art, oscillation problems arise which must be solved, for example, by decoupling a partial structure from its vibrating environment. Typical examples of this are mountings of measurement sensitive measuring apparatus in laboratories for decoupling impact noise and other disturbances by means of suitably designed damping systems, but similar problems also arise in aviation and space systems. On the other hand, it is necessary to decouple sources of disturbing vibrations from a structure surrounding them, as frequently encountered, for example, in the mountings of drive units in vehicles, aircraft or ships.
For this purpose differently designed oscillation decoupling devices are known which exert a purely passive damping of oscillating action with the use of elastic or damping materials. However, the disadvantage of these devices lie in the fact that it is not possible to adapt to changing system characteristics in order to maintain as optimum an oscillation damping as possible. Moreover, although the use of the softest possible mountings results in effective oscillation damping or oscillation decoupling, this is also associated with imprecise mounting of the decoupled system. On the other hand, although stiffer mounting systems allow more precise system positioning, the quality of the oscillation decoupling suffers correspondingly, particularly in the case of oscillations with small amplitudes and high frequencies.
In addition to purely passively designed oscillation decoupling systems, mechatronic and adaptronic solutions are being used to an increasing extent. The oscillation decoupling is achieved by means of actively introduced compensation signals which serve for the controlled activation of electrodynamic actuators, magnetic bearings or piezo-actuators which are integrated in the region of oscillation decoupled interfaces and make an active contribution to oscillation decoupling, in the sense of an oscillation reduction, for the specific coupling of counter-oscillations.
Reference is made, by way of example, to U.S. Pat. No. 5,645,260, which describes an oscillation decoupling device which is provided between a load and a vibrating background. The load rests essentially on an elastic support structure in the form of a jib angle along whose jib elements, orientated perpendicularly to each other, are installed flat piezo-actuators which are capable of inducing both horizontally and vertically directed oscillations into the jib angle due to their arrangement orientated orthogonally to each other, with the ultimate object being effective oscillation decoupling. The prior art arrangement of the piezo-actuators also has the advantage that the actuators are largely protected from damaging mechanical loads by the support structure.
A further modular interface for damping mechanical oscillations is disclosed in DE 103 61 481 A1, which provides for a plurality of energy converter systems kinematically coupled to each other between a basic connecting element and a load connecting element. These systems, in a similar manner to the oscillation decoupling system explained above, are based on the specific control of piezoelectric converter materials. However, the energy converter systems, designed as piezoelectric stacking actuators, are operated under mechanical pretension and are protected against loading by shearing and torsion. Therefore, there is a need for comprehensive mechanical protective measures for the actuators.
The oscillation decoupling devices of the prior art predominantly represent systems that are individually adapted to certain interfaces between two components to be oscillation decoupled. These systems cannot be used in other systems to be decoupled or can only be used in them with expensive design modifications. Moreover, the integration of the piezo-actuators in the structure concerned represents a high construction expenditure which is unavoidably associated with high production and assembly costs.